Request

Note: This feature is available in Web Workers.

The Request interface of the Fetch API represents a resource request.

You can create a new Request object using the Request() constructor, but you are more likely to encounter a Request object being returned as the result of another API operation, such as a service worker FetchEvent.request.

Constructor

Request(): Creates a new Request object.

Instance properties

Request.body Read only: A ReadableStream of the body contents.
Request.bodyUsed Read only: Stores true or false to indicate whether or not the body has been used in a request yet.
Request.cache Read only: Contains the cache mode of the request (e.g., default, reload, no-cache).
Request.credentials Read only: Contains a value controlling whether credentials should be included with the request (e.g., omit, same-origin, include). The default is same-origin.
Request.destination Read only: A string describing the type of content being requested.
Request.duplex Read only: The duplex mode of the request, which determines whether the browser must send the entire request before processing the response.
Request.headers Read only: Contains the associated Headers object of the request.
Request.integrity Read only: Contains the subresource integrity value of the request (e.g., sha256-BpfBw7ivV8q2jLiT13fxDYAe2tJllusRSZ273h2nFSE=).
Request.isHistoryNavigation Read only: A boolean indicating whether the request is a history navigation.
Request.isReloadNavigation Read only: A boolean indicating whether the request is a user-triggered reload.
Request.keepalive Read only: Contains the request's keepalive setting (true or false), which indicates whether the browser will keep the associated request alive if the page that initiated it is unloaded before the request is complete.
Request.method Read only: Contains the request's method (GET, POST, etc.)
Request.mode Read only: Contains the mode of the request (e.g., cors, no-cors, same-origin, navigate.)
Request.redirect Read only: Contains the mode for how redirects are handled. It may be one of follow, error, or manual.
Request.referrer Read only: Contains the referrer of the request (e.g., client).
Request.referrerPolicy Read only: Contains the referrer policy of the request (e.g., no-referrer).
Request.signal Read only: Returns the AbortSignal associated with the request.
Request.targetAddressSpace Read only: Returns the request's target address space, which indicates whether it is a loopback, local, or public request.
Request.url Read only: Contains the URL of the request.

Instance methods

Request.arrayBuffer(): Returns a promise that resolves with an ArrayBuffer representation of the request body.
Request.blob(): Returns a promise that resolves with a Blob representation of the request body.
Request.bytes(): Returns a promise that resolves with a Uint8Array representation of the request body.
Request.clone(): Creates a copy of the current Request object.
Request.formData(): Returns a promise that resolves with a FormData representation of the request body.
Request.json(): Returns a promise that resolves with the result of parsing the request body as JSON.
Request.text(): Returns a promise that resolves with a text representation of the request body.

Note: The request body functions can be run only once; subsequent calls will reject with TypeError showing that the body stream has already used.

Examples

In the following snippet, we create a new request using the Request() constructor (for an image file in the same directory as the script), then return some property values of the request:

const request = new Request("https://www.mozilla.org/favicon.ico");

const url = request.url;
const method = request.method;
const credentials = request.credentials;

You could then fetch this request by passing the Request object in as a parameter to a fetch() call, for example:

fetch(request)
  .then((response) => response.blob())
  .then((blob) => {
    image.src = URL.createObjectURL(blob);
  });

In the following snippet, we create a new request using the Request() constructor with some initial data and body content for an API request which needs a body payload:

const request = new Request("https://example.com", {
  method: "POST",
  body: '{"foo": "bar"}',
});

const url = request.url;
const method = request.method;
const credentials = request.credentials;
const bodyUsed = request.bodyUsed;

Note: The body can only be a Blob, an ArrayBuffer, a TypedArray, a DataView, a FormData, a URLSearchParams, a ReadableStream, or a String object, as well as a string literal, so for adding a JSON object to the payload you need to stringify that object.

You could then fetch this API request by passing the Request object in as a parameter to a fetch() call, for example and get the response:

fetch(request)
  .then((response) => {
    if (response.status !== 200) {
      throw new Error("Something went wrong on API server!");
    }
    return response.json();
  })
  .then((response) => {
    console.debug(response);
    // …
  })
  .catch((error) => {
    console.error(error);
  });

Specifications

Fetch